The invention relates to an osteosynthesis plating system for fixing or immobilizing several pieces or segments of adjacent bone utilizing screws which may be screwed into the segments of bone through openings provided in the osteosynthesis plate. The Osteosynthesis plate is pressed against the bone surface by the screws and fixed thereto. In particular, the invention relates to an extension plate for use with a previously implanted osteosynthesis plate for fixing additional adjacent segments of bone during a subsequent surgery.
Skeletal parts in human and animal bodies, particularly articulated skeletal segments, are often immobilized relative to one another to allow for healing of bone injuries, for example after a fracture. Absolute immobilization is paramount for the healing of bone injuries.
For such immobilization purposes, osteosynthesis plates of the type disclosed in U.S. Pat. No. 4,503,848 are utilized in surgical repair and immobilization of bone injuries.
However, typically the need may arise where a second surgery is required to repair bone injuries to adjacent bone segments. The current procedure requires that the previously implanted plate be removed completely in order to replace it with a longer plate such that the adjacent bone segment and the originally immobilized bone segments can now be immobilized by a single osteosynthesis plate. To remove the previously implanted plate, each screw must be removed, some of which screws may be overgrown with bone. Explanting of these screws is a time consuming process which is very invasive and risky for the patient.
The object of the present invention is to provide a system of immobilizing adjacent segments of bone in a second surgery wherein the removal of a previously implanted osteosynthesis plate is avoided. In this manner the disadvantages associated with removal of the previously implanted plate are avoided. Therefore, the advantages provided by the present invention include a reduction in surgery time and a less invasive surgical procedure. In addition, the cost associated with the extension plate is lower compared to a longer replacement plate. Surgical costs are decreased as well due to the reduction in surgical time required.
Corresponding apparatus and methods are provided.
The invention relates to a method and apparatus for immobilizing adjacent bone segments. An osteosynthesis plating system is provided for fixing or immobilizing several pieces or segments of bone utilizing screws which may be screwed into the segments of bone through openings provided in the osteosynthesis plate (sometimes referred to herein as xe2x80x9cbone platexe2x80x9d). The osteosynthesis plate is pressed against the bone surface by the screws and fixed thereto. In particular, the invention relates to an osteosynthesis extension plate for immobilizing adjacent segments of bone in a second surgery wherein the removal of a previously implanted osteosynthesis plate is avoided.
In a particular embodiment, an osteosynthesis extension plate is provided for immobilizing at least two adjacent bone segments by means of screws which may be screwed into the bone segments through openings in the extension plate. The extension plate is generally defined by longitudinal edges and transverse edges, the plate having a greater longitudinal dimension than transverse dimension. The extension plate has a first bone contacting surface and a second non-bone contacting surface. The extension plate is further defined by a thick plate portion and a thin plate portion. At least two rows of pairs of through openings are provided in the extension plate. A first pair of through openings is arranged in the thick portion of the plate and a second pair of through openings is arranged in the thin portion of the plate such that the thin portion of the plate can be inserted underneath and affixed between a second osteosynthesis plate and a bone segment. The thick portion of the extension plate is affixed to an adjacent bone segment by screws, thereby immobilizing an adjacent bone segment.
In a further embodiment of the invention, the thin portion of the extension plate can be positioned underneath the thick portion of an identical extension plate to provide for immobilization of adjacent bone segments. In this manner several identical extension plates can be piggybacked by placing the thin portion of one extension plate underneath the thick portion of another extension plate to immobilize several adjacent bone segments.
In another embodiment of the invention, the extension plate is curved in the direction transverse to its longitudinal axis such that the first bone contacting surface is concave. Such a configuration of the first bone contacting surface allows for better contact with the surface of the bone segment to be immobilized.
In a further embodiment of the invention, the osteosynthesis extension plate is used to immobilize bone segments during a second surgery where a previously implanted osteosynthesis plate is already affixed to an adjacent bone segment. In this embodiment, the screws holding the previously implanted plate to the adjacent bone segment are removed and the thin portion of the extension plate is inserted underneath the previously implanted plate such that the screw holes of the previously implanted plate and the screw holes of the extension plate are in alignment. The screws are then reinserted into the bone through the previously implanted plate and the thin portion of the extension plate. The thick portion of the extension plate is screwed into the adjacent bone segment thereby immobilizing the adjacent bone segment. In this manner, a bone segment adjacent to a previously injured and immobilized bone segment can be immobilized without completely removing a previously implanted plate. In other words, only the screws holding the previously implanted plate to the adjacent bone segment are removed, not all screws holding the previously implanted plate to all the previously immobilized bone segments need be removed.
In a further embodiment of the invention, the thick portion of the extension plate may have more than one row of through openings for immobilization of more than one adjacent bone segment. In this embodiment, the extension plate has a greater longitudinal dimension in order to extend over more than one adjacent bone segment. Pairs of holes are positioned such that each adjacent bone segment can be affixed by two bone screws. The number of adjacent bone segments that can be immobilized in this manner may be two, three, four or more.
In a further embodiment of the invention, the through openings are elongated slots. The elongated slots provide for ease of positioning and alignment of the extension plate, particularly when the extension plate is used in connection with a non-identical previously implanted plate or when the respective bone segments to be immobilized are not of uniform dimension.
In another embodiment of the invention, the elongated slots arranged in the thin portion of the plate are open-ended at the transverse edge of the thin portion of the plate. Such a configuration enables the extension plate to be affixed between a bone segment and a previously implanted plate without complete removal of the bone screws of the previously implanted plates. In such a configuration, the screws holding the previously implanted plate to the bone segment adjacent to the injured bone segment need only be loosened such that the thin portion of the extension plate can be slid into position. The extension plate is inserted between the bone segment and the previously implanted plate such that the open-ended slots of the thin portion of the extension plate fit around the loosened screws of the previously implanted plate. The screws are then re-tightened and the thick portion of the extension plate is screwed into the adjacent bone segment. In this manner, a bone segment adjacent to a previously injured and immobilized bone segment can be immobilized without completely removing the screws from a previously implanted plate.
In a further embodiment of the invention, the open-ended slots have beveled edges for ease of insertion underneath a previously implanted plate.
In another embodiment of the invention, the thin plate portion of the extension plate is provided with side rails arranged at the longitudinal edges of the thin plate portion which extend above the second non-bone contacting surface of the extension plate. When the extension plate is positioned underneath the second osteosynthesis plate the side rails are substantially parallel to edge surfaces of the second osteosynthesis plate.
The side rails may interlock with grooves cut into the edge surfaces of the second osteosynthesis plate.
In an alternate embodiment of the invention, the extension plate is generally defined by contoured longitudinal and transverse edges. The thick plate portion has at least one row of pairs of through openings. The thin plate portion has at least one through opening. The thick plate portion of this embodiment has a substantially larger transverse dimension than the thin plate portion. The thin plate portion is dimensioned to fit within a groove provided in a non-bone contacting surface of a second osteosynthesis plate such that the thin plate portion can be affixed to a non-bone contacting surface of the second osteosynthesis plate without the need to remove existing screws affixing the second osteosynthesis plate. The thin plate portion of the extension plate may be affixed to the second plate by means of one or more screws and the thick plate portion may be affixed to the adjacent bone segments by means of one or more screws. The thin plate portion of the extension plate in this embodiment may comprise a T-shaped portion extending from the thin plate portion which fits within a corresponding groove in the second plate.
In a further embodiment, the extension plate has a plate portion having at least one row of pairs of through openings with two extension arms extending longitudinally from the plate portion. The extension arms are dimensioned to fit alongside a second osteosynthesis plate. The plate portion may be affixed to the second osteosynthesis plate by a clamping device and to the adjacent bone segment by screws.
In an alternate example embodiment, a groove may be provided in each of the extension arms for accommodating lengthwise edge surfaces of the second osteosynthesis plate when the extension plate is positioned adjacent the second osteosynthesis plate. The groove may extend from a tip of one extension arm to a tip of the other extension arm.
A contoured section may be provided which extends between a base of each extension arm. The contoured section may be adapted to conform to a contoured transverse edge of the second osteosynthesis plate.
An additional single through opening may be positioned in a center portion of the plate portion above the at least one row of pairs of through openings. Bone screws may be inserted through the at least one row of through openings and through the single through opening for securing the extension plate in place in a bone segment and adjacent the second osteosynthesis plate.
The through openings may comprise elongated slots.
Multiple extension plates may be used to immobilize multiple adjacent bone segments.